#!/bin/sh
set -e

usage () {
    echo "usage: git committer-info [-aAh] <pattern> [<pattern> ...]" >&2
    echo >&2
    echo "Show contribution stats for any committer matching the given pattern." >&2
    echo >&2
    echo "Options:" >&2
    echo "-A    Consider all branches (instead of only the current branch)" >&2
    echo "-a    Print for all committers" >&2
    echo "-h    Show this help" >&2
}

all_branches=0
all_committers=0
while getopts aAh flag; do
    case "$flag" in
        a) all_committers=1;;
        A) all_branches=1;;
        h) usage; exit 2;;
    esac
done
shift $(($OPTIND - 1))

if [ $all_committers -eq 1 ]; then
    committers=$(git shortlog -s | cut -f2-)
else
    if [ $# -eq 0 ]; then
        usage
        exit 2
    fi
    committers=$(for item in "$@"; do echo "$item"; done)
fi

count_by_dow () {
    awk '
    BEGIN {
        map["Mon"] = 0
        map["Tue"] = 0
        map["Wed"] = 0
        map["Thu"] = 0
        map["Fri"] = 0
        map["Sat"] = 0
        map["Sun"] = 0
    }

    {
        map[$1] += 1
    }

    function round(x, ival, aval, fraction)
    {
        ival = int(x)    # integer part, int() truncates
     
        # see if fractional part
        if (ival == x)   # no fraction
           return ival   # ensure no decimals
     
        if (x < 0) {
           aval = -x     # absolute value
           ival = int(aval)
           fraction = aval - ival
           if (fraction >= .5)
              return int(x) - 1   # -2.5 --> -3
           else
              return int(x)       # -2.3 --> -2
        } else {
           fraction = x - ival
           if (fraction >= .5)
              return ival + 1
           else
              return ival
        }
    }
     
    END {
        total = map["Mon"] + map["Tue"] + map["Wed"] + map["Thu"] + map["Fri"] + map["Sat"] + map["Sun"]
        printf("%s %6s %4s%%\n", "Mon", map["Mon"], round(map["Mon"] / total * 100))
        printf("%s %6s %4s%%\n", "Tue", map["Tue"], round(map["Tue"] / total * 100))
        printf("%s %6s %4s%%\n", "Wed", map["Wed"], round(map["Wed"] / total * 100))
        printf("%s %6s %4s%%\n", "Thu", map["Thu"], round(map["Thu"] / total * 100))
        printf("%s %6s %4s%%\n", "Fri", map["Fri"], round(map["Fri"] / total * 100))
        printf("%s %6s %4s%%\n", "Sat", map["Sat"], round(map["Sat"] / total * 100))
        printf("%s %6s %4s%%\n", "Sun", map["Sun"], round(map["Sun"] / total * 100))
        printf("     -----\n");
        printf("    %6s\n", total);
    }
    '
}

indent () {
    sed -Ee 's/^/    /'
}

opts=""
if [ $all_branches -eq 1 ]; then
    opts="--all"
fi

first=1
echo "$committers" | while read committer; do
    if [ $first -ne 1 ]; then
        echo ""
    else
        first=0
    fi
    echo "$committer:"
    git log $opts --author="$committer" --format="%ad" | count_by_dow | indent
done
